Process of rockslide induced by underground mining and penetration: A case study of Pusa rockslide in Nayong County, China

To explore the disaster mechanism of the slope with steep upper structure and slow lower structure in the karst mountainous area of southwest China. Take the Pusa Rockslide as an example. The deformation and failure characteristics of the slope under the action of dead weight, mining and rainfall were studied by Continuum－Discontinuum Element Method (CDEM) numerical simulation based on field geological investigation. The results show that the evolution process of the Pusa rockslide can be divided into six stages as follows:(1) Natural Evolution: The upper limestone is dissolved, which creates favorable conditions for the generation and development of cracks; (2) Disturbance Deformation: The mountain is affected by underground mining, which causes the slope to produce a subsidence deformation of about 2m; (3) Collapse Deformation: The roof of the goaf bends, sinks and collapses. A deep and large crack of about 200 m is formed at the trailing edge of the slope; (4) Extrusion Deformation: The formation of potential collapse failure surface－Similar Cantilever; (5) Instability and Failure: The landslide mass breaks through the "locking section"; (6) Energy Dissipation: The rockslide mass is broken and scrapes the rock and soil along the way to form a debris flow. The instability mechanism of the slope is Goaf－Tensile Crack－Creep－Shearing (Toppling)－Energy Dissipation－Accumulation.